Process for stabilizing hydrocarbons



ct. 24, 1950 c. MORRIS PROCESS FOR STABILIZING HYDROCARBONS Filed July 11, 1946 82m mx h filllrl mm: 0F IL N 1 9 wo mo5 ll A 1 Q m h 9 motmiZ m lav km Q 1:] ll! um: mo Em F5555 0P m motmizm INVENTOR. L c MORRIS ATTORNEYS Patented Oct. 24, 1950 rnocnss ron s'rannazmc mnmocrmnons Lloyd 0. Morris, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware Application July 11, 1946, Serial No. 682,765

6 Claims. (Q1. 4H8) This invention relates to the stabilization of hydrocarbons. In one particular aspect it relates to methods of stabilizing hydrocarbon oils against deterioration caused by oxygen and in another particular aspect it relates to novel reagents for preventing such deterioration. In still another aspect it relates to a method of distillation wherein such novel'reagents are added to the feed to a distillation process.

It is common knowledge that many hydrocarbon materials, particularly those containing unsaturated compounds, deteriorate when oxygen is present, with formation of gummy substances, oxygenated hydrocarbon derivatives, and in some instances with the development of objectional odors. While such deterioration processes are more common in materials containing unsaturated compounds, some saturated hydrocarbons exhibit the tendency to develop unpleasant odor when heated in the presence of air. This tendency to develop unpleasant odor is especially marked in materials containing substantial proportions of highly branched aliphatic alkylates, similar to the alkylates used extensively in high octane motor fuels, because of the large number of tertiary carbon atoms present in such materials. Often this development of odor is accompanied by the formation of oxygenated hydrocarbon derivatives whose exact structure is not clearly understood but which include aldehydes, ketones, carboxylic acids, the'unstable compounds known as peroxides, and the like. Such deterioration frequently renders a hydrocarbon material undesirable for many otherwise valuable potential uses.

Methods for preparing fractions of highly branched parafiin hydrocarbons having substantially no odor are described in copending applications of Legatskiand Crawford, Serial No. 616,930, now Patent 2,468,986, filed September 17, 1945; Crawford and Morris, Serial No. 617,870, now Patent 2,463,601, filed September 21, 1945; and Axe, Serial No. 675,531, now Patent 2,523,459, filed-lune 10, 1946. After preparation of these substantially odorless fractions storageof the product has often been accomplished in containers from which oxygen was excluded by blanketing with a non-oxidizing odorless gas; such as that formed by the method taught in the copending application of Glidden,

Serial No. 651,031, filed February 28, 1946. As an alternative for these obviously cumbersome 2 procedures the addition of stabilizers such as phenols and phenolic derivatives have been employed in some instances. However, the intrinsic disagreeable odors of such phenolic compounds has rendered their use objectional in many cases.

It is an object of this'invention to provide a method for stabilizing hydrocarbon materials against deterioration caused by oxidation.

Another object is to provide a method for preventing development of undesirable odor in hydrocarbon materials containing substantial proportions of highly branched paraflin hydrocarbons.

Another object is to provide novel oxidation inhibitors capable of greatly reducing or preventing deterioration of hydrocarbon materials by oxidation.

Another object is to provide a method of preparing substantially odorless fractions of highly branched paraflin hydrocarbons.

Other objects and advantages will be apparent to those skilled in the art as this disclosure proceeds.

I have found that deterioration due to oxidation in hydrocarbon materials and particularly in those hydrocarbon materials containing substantial proportions of highly branched paraflin hydrocarbons can be eliminated or substantially reduced by incorporating small proportions of certain high-molecular weight organic salts of certain heavy metals therein. I have also found that heating and/or distilling such hydrocarbons can be effected to provide substantially odor free products when one of the oxidation inhibiting agents of this invention is added to the hydrocarbon material and is present during such heating or distillation process.

The novel inhibiting agents of my invention comprise the stannous, ferrous, cobaltous and nickelous salts of high molecular weight fatty acids containing not more than one unsaturated linkage to the molecule, such as the stearates. palmitates, oleates and the like. Particularly I prefer to use the stannous salts of fatty acids selected from the group consistingof the saturated and mono oleflnic unsaturated fatty acids having from 16 to 18 carbon atoms, inclusive,- per moiecule, of'which the .stearate, palmitate, and oleate are representative. In the practice of my invention I have generally preferred to operate with stannous stearate as an oxidation inhibitor 3 I/ because of its more ready availability and because of the preferred color characteristics of the hydrocarbon product containing this inhibitor.

In general under conditions where moderate oxidation is to be expected I prefer to use about 0.05 to 0.10 weight per cent of inhibitor in the hydrocarbon material to be stabilizedalthough as much as 0.5 per cent may be sometimes desirable and under other conditions as little as 0.005 per cent may be effective. The amount to be used will vary somewhat with the degree of heating expected to be encountered, the proportion of oxygen in gases in contact with such hydrocarbon materials, degree of exposure to air or oxygen, etc. In all cases the proportion of inhibitor to hydrocarbon is quite small.

The oxidation inhibitors of my invention may be employed not only to inhibit oxidation in bydrocarbon materials during storage or use but also in distillation processes for the manufacture of substantially odorless fractions of highly branched paraflln hydrocarbons. The attached drawing illustrates diagrammatically a process for preparing such fractions by a method embodying my invention.

Referring thereto, a. feed comprising highly branched paraflin hydrocarbons enters via line I and is introduced into a medial portion of a conventional fractionation tower 2. From 0.005 to 0.50 per cent of a stannous, ferrous, cobaltous or nickelous salt of a high molecular weight fatty acid having not more than one olefinic bond per molecule is continuously introduced into and admixed with the incoming feed via line 3. Distillation is conducted intower 2 by methods well known in the art, using reflux. It may frequently be desirable to withdraw the fraction of distillate required as side stream via. line 4. Such procedure is indicated when the feed contains odorous materials of slightly greater volatility than the product desired. These may be distilled off overhead and discarded. From 0.005 to 0.50 per cent of an oxidation inhibitor of the type mentioned above are added to the product via line 6. The product is then conducted to stripper l where materials boiling below the initial boiling point of the desired product are removed via overhead line ii. The desired product, containing inhibitor is withdrawn via line H tostorage l2.

When the feed does not contain an appreciable quantity of volatile odorous materials the product may be withdrawn via line 5. The oxidation inhibitor may be added either to the product line or to the product in suitable storage vessels. The portion of the drawing showing the line from the top of tower l0 and the circuit back to the upper portion of the tower portrays a conventional reflux arrangement.

In any event it is frequently necessary to discard a small amount of the initial product which distills while considerable quantities of air are in the apparatus.

A salient advantage of the present invention lies in the simplicity of my process as compared to methods involving blanketing distillation and storage apparatus with inert odorless gas. Other obvious advantages are due to the persistence of the stabilizing eflfect imparted, the broad field of low cost materials made available for the production of liquid hydrocarbon fractions having low odor intensity, the freedom from intrinsic odors imparted by the inhibitor, and other features which will be apparent to those skilled in the art.

While I have described one particular embodiment of my invention as applied to mixtures of saturated hydrocarbons comprising a substantial proportion of branched chain paraflins, its utility as applied to other types of hydrocarbons susceptible to similar deterioration will be apparent and such application is within the scope of this invention.

Example I H H ea mg ea mg on n Inhibitor Time Temp Odor PPMQS None None None.... None.... 7 0

o 15 min.. Boiling- Rancid 110 0,1 part stannous Sfeamip (in (In N mm 2 Do 24 hrs." do do Do 48 IRS. (in (in 3 Example II The experiment of Example I was repeated employing 0.05 parts by weight of stannous oleate as the stabilizing agent. Conditions and procedure were substantially as before. The results are shown in the following tabulation.

' H r H t' gewgde ea ing ea mg on nt Time Temp.- PPM(as None None None.--. None 0 o l5min Boiling Rancid. 110 .OSpartStannousO do do None 0 Do 180 mindo. do 0 Having described my invention and explained its operation, I claim:

1. The process of preparing substantiallyodorless fractions of highly branched paraflin hydrocarbon mixtures while avoiding odor formation caused by oxidative deterioration while heating which comprises adding from 0.005 to 0.5 weight per cent of a stannous salt of a fatty acid selected from the group consisting of saturated and monoolefinic unsaturated fatty acids containing from 16 to 18 carbon atoms per molecule to a mixture of highly branched paraflin hydrocarbons, subjecting the resulting mixture to fractional distillation in a fractionating tower heated at the bottom and refluxed at the top, withdrawing a relatively small proportion of overhead conodorous materials, and withdrawing a REFERENCES CITED The following references are of record in the tile 01' this patent:

Certificate of Correction Patent No. 2,526,963

LLOYD C. MORRIS 6 UNITED STATES PATENTS Number Name Date Ditmar Mar. 13, 1923 Rather et a1 Mar. 13, 1934 Lachman Mar. 31, 1936 Mizuta May 11, 193'! Amos June 15, 1948 October 24, 1950 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 43, for the patent number 2,523,459 read 9,523,549;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 1st day of May, A. D. 1951.

THOMAS F. MURPHY,

Assistant Oomnz'ssz'omr of Patents. 

1. THE PROCESS OF PREPARING SUBSTANTIALLY ODORLESS FRACTIONS OF HIGHLY BRANCHED PARAFFIN HYDROCARBON MIXTURES WHILE AVOIDING ODOR FORMATION CAUSED BY OXIDATIVE DETERIORATION WHILE HEATING WHICH COMPRISES ADDING FROM 0.005 TO 0.5 WEIGHT PER CENT OF A STANNOUS SALT OF A FATTY ACID SELECTED FROM THE GROUP CONSISTING OF SATURATED AND MONOOLEFINIC UNSATURATED FATTY ACIDS CONTAINING FROM 16 TO 18 CARBON ATOMS PER MOLECULE TO A MIXTURE OF HIGHLY BRANCHED PARAFFIN HYDROCARBONS, SUBJECTING THE RESULTING MIXTURE TO FRACTIONAL DISTILLATION IN A FRACTIONATING TOWER HEATED AT THE BOTTOM AND REFLUXED AT THE TOP, WITHDRAWING A RELATIVELY SMALL PROPORTION OF OVERHEAD CONTAINING ODOROUS MATERIALS, AND WITHDRAWING A DISTILLATE FROM SAID FRACTIONATING TOWER CONSISTING OF A SUBSTANTIALLY ODORLESS HYDROCARBON FRACTION OF DESIRED BOILING RANGE. 